The applicant has previously proposed the above-mentioned kind of wheelchair (in Japanese patent application Nos. Hei-7-172086, Hei-7-27397, etc.) in which right and left hand wheels are respectively provided with electric motor drive units energized with a battery disposed on one wheel side through electric cables and a main switch.
However, since the motor-operated wheelchair proposed as described above has the main switch attached on the vehicle body frame side, there is a problem that one has to take pains in deciding how to route the long cable interconnecting the main switch and the electric motor unit.
Another problem with such a kind of wheelchair is that when it is intended to make the wheels and the electric motor units removable from the vehicle body frame for the convenience of transport, an electric cable coupler has to be interposed somewhere along the electric cables between the main switch and the electric motor unit so that the electric cables and the wheel may be disconnected at the coupler. This increases the number of components and makes the constitution complicated.
Therefore, an object of the invention is to provide a motor-operated wheelchair which is simple in constitution and facilitates attachment and removal of the wheels while minimizing the number of electric cables and associated components.
By the way, the motor-operated wheelchair having right and left wheels including respective electric motor units removable from the vehicle body frame requires rotation holding structure because the driving reactional forces of the electric motor units must be received with the vehicle body frame.
However, the conventional rotation holding structure is such that the rotation of the electric motor unit is held by mutual engagement of metallic components and therefore uncomfortable metallic noise is produced from the rotation holding structure every time the intermittent driving force (assist force) occurs.
Therefore, another object of the invention is to provide a motor-operated wheelchair in which the wheels may be attached and removed without play or rattle, and abnormal noise is prevented from being produced.
Another problem with the motor-operated wheelchair is that, since the battery is disposed only on the side of one wheel, the electric cable for energizing the electric motor unit on the other wheel becomes long, and one has to take pains to decide how to lay the cable to the electric motor unit on the other wheel.
The necessary length of the electric cable varies with the battery mounting position and the size and type of the wheelchair. Therefore, the cable length is usually set to a certain value having some margin so that the same cable and electric motor may cover all types and sizes of the wheelchair. The surplus cable length brings about another problem of slack along the cable depending on the size of the wheelchair.
Another problem with the conventional motor-operated wheelchair is that, since the coupler for interconnecting the electric cables is exposed outside, the coupler cannot be made highly water-proof and so may invite electric troubles.
Therefore, another object of the invention is to provide a motor-operated wheelchair capable of absorbing slack in the electric cables, and preventing electric troubles from occurring clue to water infiltration.